


Follow My Song

by ThereWillBeCubes



Series: Yandere Free! [4]
Category: Free!
Genre: M/M, Yandere, blood warning, mer!sousuke, siren!Ai, siren!au
Language: English
Status: Completed
Published: 2016-02-03
Updated: 2016-02-03
Packaged: 2018-05-18 00:31:07
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,140
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5891104
Author URL: https://archiveofourown.org/users/ThereWillBeCubes/pseuds/ThereWillBeCubes
Summary: <blockquote class="userstuff">
              <p>Alone one night, Sousuke meets a strange merman named Ai, exiled from his old clan and without a home.<br/>He's unlike any other he's ever seen before.</p>
            </blockquote>





	Follow My Song

**Author's Note:**

> I already uploaded this to my writing blog, yanderayy.tumblr.com but felt like uploading something here  
> There are more short drabbles/stories there, and you're free to request something for me to write!

-

 

The moonlight diffuses through the shifting waters, fluidly shifting colours of blue and green that put Sousuke at quiet ease. He's alone; while he enjoys the company of his clan-mates, he often prefers to swim in silence, in the endless waters and their peace.

He makes his way to the warmer sands, where the water is shallower and the plants more plentiful, hoping to perhaps feel them against his skin. They held the radiance of the sun, even after it left.

A movement disturbs his placid thoughts.

His body tenses, and he scents the water, finding the faint smell of mer, and little else.

Sousuke frowns, scouring the greenery.

The plants sway in the current, but he's certain it was something else-

“Hello.”

Sousuke stops, watching as a head pops out of the seaweed.

It's another mer, alright, this one no-one he'd ever seen before. Silver-grey hair floats around a delicate, pale face, set with floaty, pretty fins and a pair of piercing blue eyes that reminded Sousuke of clear skies.

“Hello,” he replies carefully, “who are you?”

“I'm Ai,” the mer answers, “who are you?”

“Sousuke.”

To his surprise, Ai inches closer, summer eyes filled with curiosity, and the body that parts the dark-green plants is pearly white, arms rippling with lean muscle.

“What are you doing here?” Sousuke asks. Whoever he was, he was far from home.

“I was about to start hunting.”

That's not quite the answer he was looking for, but he watches as Ai stretches out on his back, seemingly at ease.

“I've never seen someone like you before,” Sousuke tries.

Ai smiles, settling down in the moss bed, tail languidly shifting. It glimmers softly with silvery luminescence, and in the night-darkened waters the multi-layered colours move almost hypnotically, relaxing.

“I usually don't stay close to the surface during the day,” he says, stretching out with pale limbs, “I prefer the dark.”

Sousuke drifts closer, his eyes travelling up Ai's body. His scales are in stripes of silver and dark grey, like layered stormclouds, and his fins are short and billowing, too decorative for hunting, Sousuke thinks.

“Isn't it difficult to find food in the dark?” Sousuke asks, and Ai tilts his head, smile turning sly.

“I've been quite lucky so far, food seems to find me,” he replies. Sousuke doesn't know what to make of that; it's oddly cavalier.

Ai turns over onto his belly, and Sousuke's eyes widen at the sight of jagged cuts on his back, cutting through his spinal fins with grotesque curves. Some still look inflamed, red and swollen even as they begin to scar.

“You're hurt,” he murmurs, throat tight, coming close, hands reaching out. He stops himself before he touches them, suddenly remembering Ai is not from his clan, and probably wouldn't react kindly to a stranger's hands upon him.

Ai rolls his head to the side, eyeing Sousuke.

“I'll get better,” he says, non-committally.

“What did this to you?” Sousuke continued; eyes roaming over his skin, noticing other nicks and bite-marks.

Ai sighs.

“A member of my clan,” he mutters, “well, ex-clan. We had a... disagreement.”

“A disagreement?” Sousuke asks in disbelief. Whatever it was, the cuts looked vicious.

“Over food,” Ai says simply, “I had to leave.”

He sounds subdued, and Sousuke doesn't ask for more information; he was probably sick of thinking about it.

“Do you have anywhere to go?”

The merman looks at him in surprise, eyes widening, before he shrugs, settling down again.

“Not really.”

Sousuke bites the inside of his cheek. It wasn't his place to invite him to his clan, nor could he fully trust him, but leaving him alone out here didn't sit right.

“... I could take you to meet my clan elders. I'm sure they'd be happy to welcome a new member.”

Another surprised expression, warmer, but reticent.

“...thank you for the offer, but I'd rather stay on my own.”

There's nothing Sousuke can do about that, so he nods. Ai stretches, and stares upwards to the surface.

“I should probably hunt,” he murmurs, “I'm hungry.”

Sousuke follows his eyes curiously, but like he thought, there was nothing there. Ai lifts from the seabed.

“It was nice meeting you, Sousuke, perhaps we'll meet again.”

“Perhaps.”

Sousuke watches as he flicks his tail, surging away with surprising speed and grace, rising towards the surface.

The plants are soft on his skin, and he realises just how tired he is. He'd be useless in the morning hunt if he didn't return home to sleep.

Swimming away, he goes to give Ai one last glance, but he can no longer see him in the shifting moonlit waters.

 

-

 

The water around him is warm, gentle, lulling him into sleep. His hunt had been successful, his belly full, and the moss was so comfortable, so soft... he'd stayed out too late last night, maybe just a quick nap...?

“Sousuke?”

 _Go away,_ he thinks, _too sleepy._

“Sousuke.”

Sousuke shifts, deciding he shouldn't ignore the voice. He lifts his head to see Seijuro, his powerful tail moving sharply as he comes to a halt, golden eyes sharp and wary.

“Can I talk to you for a moment?”

“What is it?”

Seijuro is unusually sombre as he speaks, a weight in his words and expression.

“There's been increased human activity in the waters, and some of the elders are worried about possible hunting.”

Sousuke frowns at this. He trusted the elder's experience, but rarely were they in the open waters anymore, and on all accounts there hadn't been any problems with human ships lately.

“It increases in different cycles, what's the issue?”

“The issue is no matter what is happening, we need more on the watch. At least for a short while.”

Sousuke has to stop himself from growling. He was strong and large, but wasn't made for fighting like Seijuro or Rin. His claws were duller, teeth more suited for grinding than for ripping, and he didn't have their agility and perception. He would do anything for the clan, but he was far more suited to hunting and food-collecting.

Seijuro can still see his displeasure writ on his face, because his voice is placating and diplomatic, “we don't expect you to fight anything, just join the scouts for a cycle.”

His eyes are solidly staring at him, but Sousuke knows he's pointedly avoiding his tail, a reminder of the last time he protected the clan, mottled with scars.

“Please, Sousuke,” Seijuro says quietly, “until this calms down again.”

“I don't want to be... too tired to do my work,” Sousuke replies, uncomfortably aware of his almost-napping.

“The new brood can help out, there's a few hunters in the lot, don't worry.”

Sousuke sighs. Well, it's not like he didn't wander around at night anyway.

“Fine, just let me know when my first night is.”

Seijuro beams at him, his usual energy returning as he claps Sousuke on the back, “knew I could count on you! Here-”

He digs around in his bag, producing several fish, “as thanks! See you tonight!”

He swims away, golden tail flashing in the water before Sousuke can respond, growling to himself about the sudden work. The fish in his hands are plump, the silver scales shining and smooth, but he was completely full and satiated.

The silver pulls his thoughts to the lonely Ai, and Sousuke wonders if he's still out in the darker plant fields, if he's hungry.

Mind made up, he takes the fishes' tails in a tight grip and heads down, skimming the seabed to the deeper waters.

 

-

 

Ai's asleep when Sousuke finds him, nestled in the soft plants, fins languidly rippling in the water.

He looks so vulnerable, so alone, and Sousuke's heart tightens slightly. Why didn't he accept his offer? It was dangerous to live outside of a clan.

He's not sure what to do, watching Ai sleep, clutching the fish, and considers leaving them by his side. But would the smell attract any predators? They rarely came around, but they could if they were tempted.

A quiet, sleepy voice breaks through his thoughts.

“Sousuke?”

Ai keeps his head low, eyes blinking languidly, “what are you doing here...?”

He sniffs, and his pupils dilate at the sight of the fish, gills flaring.

“Are... are those for me?” he asks softly, as if he couldn't quite believe it. Sousuke nods, awkwardly lowering so he can take them.

“Yeah, I thought you might be hungry, just, hunting alone...” he replies, and Ai stares at him as if he's grown a second tail. Sousuke thrusts the fish towards him, feeling more uncomfortable by the second.

“Thank you, Sousuke,” Ai murmurs, colour filling his pale cheeks, smiling beautifully, “this is... so generous of you...”

“Uh. Yeah, I guess so-”

His mumbling stops when Ai throws his arms around him, squeezing him tightly in a hug.

“Thankyou so much, Sousuke, this will help.”

“I'm glad.”

Ai rips into the fish with gusto, and the sharpness of his teeth surprises Sousuke; he didn't look like a warrior, but his teeth rivalled Rin's in their pointed tips, bright white and deadly-looking.

Ai's throat growls as he strips the flesh of the bone with his tongue, pink and agile, and Sousuke finds himself oddly mesmerised.

He makes quick work of them, gills fluttering, and tail swishing in seeming agitation.

“That was good, Sousuke,” he says, licking the bones, “fish tastes pretty good...”

He grins, and his eyes are alight with newly-whet hunger.

“Maybe something else will find me tonight.”

 

-

 

Sousuke glides through the water, his mind quiet, not from peace, but weariness. His limbs and tail feel heavy, tired, almost soft with sleepiness. All he had to do was swim the stretch, keep an eye out, and hope everything was quiet. The waters slowly became darker, and he could feel the pull of the waves growing stronger, the current surging with upset. A distant rumbling confirmed his thoughts; thunderstorm.

Sousuke could barely see a thing in the water, and storms above seemed to call to him; wild and beautiful. With a quick check around him, he surges toward the surface, smiling as the water heaves around his body.

Salt-filled wind whips his hair, and fills his ears with it's rushing. Sousuke takes a deep breath, taking in the fresh water scent, the strange smell that could only come from the very skies being pulled apart. He loved it.

A beautiful, alluring song cut through the tumultuous winds, Sousuke feeling the beat of his heart quicken at the visceral strength and sweetness of it.

Lightning flashes across the sky, thunder answering in roars, the flashes of white and blue illuminating the form of a human vessel, one of their ships, attempting to stay afloat on the waves.

Sousuke has witnessed many of these storms, and many human ships, and this one seems to be faring well against it, steering away from an outcropping of rocks that would tear it apart. He knew them well; when he was small he and Rin would sneak away to play around them, darting in and out of the tunnels and caves among them. It was dangerous, and they relished it.

The sky lights white, and through narrowed eyes Sousuke watches figures leaping from the ship, into the roiling, deadly waters.

He doesn't understand, they were winning the fight, they were-

As the waves rise, and he with them, he can see a single form, arched on the black rock, and the song slides into his ears again, alluring, sweet. Sousuke knows the humans could not understand a word the siren sung so sweetly for them, but they would draw them in nonetheless.

 

_Come my love, come to me,_

_Leave that which burdens you,_

_I'll set your heavy heart free,_

 

_Follow me, follow my song,_

_Become one with me forever,_

_In my heart where you belong._

 

Sousuke started.

The stormclouds above had broken and scattered, shed of their rain, and chips of night sky shone through the grey. It had passed, and he had not noticed. His bones crawled with cold, creeping discomfort at the thought of the time passing, and he was exposed on the surface, defenceless and deaf to the world.

It occurs to him the song has stopped.

He focuses on the rock, but the figure is gone, and there is no sight of the humans that had jumped. The song stopped, the ship was gone.

Without a second thought, Sousuke dives below the surface, heading directly for the rocks, knowing he'll find his siren.

 

-

 

The formation hides a darkened crevice, and Sousuke's stomach turns at the sight around it. Bones, cracked and stripped of flesh and marrow, litter the seafloor, the waters full of fresh human blood.

Sitting in the burgeoning moonlight, his tail curled around a rock, sits Ai, a long human leg bone in his clawed hands.

Their eyes meet, and Ai smiles slightly.

“Hello, Sousuke. Did you enjoy my singing?”

There are broken and whole bones in piles beside him, meticulously cleaned of all flesh and tendons. He can't find his voice to reply.

“I'm almost finished, don't touch my food.”

Ai cracks open the bone with terrifying ease, making satisfied sounds as he sucked down the pink marrow inside, tongue darting to scour it clean.

“You've been luring humans,” Sousuke accused, burning anger filling his veins. Ai tosses the two halves of the bone away, and they float down to nestle pearl-white in the dark sand.

“And?” Ai asks, eyes glinting. They aren't the friendly, curious ones he remembered, but coldly purposeful and filled with primal hunger. He cracks open another arm-bone and digs out the pink insides with one sharp finger, “what of it?”

“You're attracting their attention to these waters! It could be dangerous!” Sousuke growls, drawing himself higher, glowering at the infuriatingly calm Ai.

“It means more to eat,” Ai replies, licking his finger clean, “the more the better.”

“The less the better! They could hunt and kill members of my clan, Ai, if given any reason!”

Their eyes meet, and Sousuke is angered further; there's no remorse in Ai's expression, no sympathy.

“This is a good hunting ground,” Ai says, “I need the food.”

“Find a different hunting ground! Somewhere further away!”

“I can't leave,” Ai says quietly, no longer playing with his food, but staring at Sousuke with an unreadable expression, “I want to be close.”

Sousuke stares, teeth bared in a challenging snarl. If he had to fight him for the safety of his clan, he would.

“Why?” he demands, “what could be so important?”

“I need a new mate.”

Cold creeps up Sousuke's spine, and the slow beat of his heart picks up with unpleasant speed.

“A new mate?”

“Yes. My old one tried to take my kill.”

Sousuke's entire body is tensed, ready to fight. Ai's claws look incredibly sharp, and for a terrible moment he can feel them sinking into his back, giving them matching wounds.

“You killed them?” he asks hollowly. Ai's expression darkens.

“I was preparing for mating season,” he growls, “then I discover my mate is selfish. The clan didn't think it was my place, so I left.”

Ai's eyes fix on him, and Sousuke realises how badly he mistook his hunger.

“I was going to find another siren, but the currents delivered me here, and I found you.”

Sousuke doesn't want to fight him anymore, he wants to get far away as possible, far away from those sharp teeth and jagged claws and great sense of smell.

“ _I'm not letting you go for one clan.”_

Sousuke's thoughts grind to a halt, Ai's voice spearing through them, freezing them in place and shattering them. Ai rises from the seafloor, coming level with his face. His lithe tail curls around Sousuke's squeezing slightly.

“ _My old mate was weak, greedy, unsuitable,”_ Ai continues, and Sousuke's skin alights where his hands touch, trailing down his sides, _“useless. But you're different, aren't you, Sousuke?”_

Something in Sousuke's belly shifts at the sound of his name, that beautfiul voice forming it, molten and restless. Ai's waiting for him to answer, eyes lidded, and Sousuke wants to hear him speak again, wants to hear him sing again. There's no other desire in his mind but to please him.

“...yes,” he croaks, “I'm different.”

Ai smiles for him, a radiant smile, and his fins flare and alight with twinkling white, a match for the starscape far above them, eyes twin blue moons.

“ _You are,”_ he murmurs, lilting, _“you're strong, Sousuke, you're generous, you've shown me this. It makes me happy.”_

Sousuke can't help but feel thankful, his own mouth curving into a grateful smile, skin burning now. Ai's arms are wrapped tightly, his body pressing close.

“It... does?”

“ _Very happy. Does that make you happy?”_

 _Yes, yes yesyesyes_ Sousuke thinks desperately, his own thoughts melding into Ai's, until he can't tell where his desires seperate from the siren's, disordered and at odds with buried needs and wants. There was something that they stuck upon, something he should be remembering. Something else that mattered.

“ _They don't,”_ Ai whispers, smile gone, hands gripping in Sousuke's hair so he can put his lips by his ear, _“our needs are the same, Sousuke.”_

He rolls his tail against Sousuke's, and Sousuke growls as heat warms his scales, burying his nose in Ai's neck to smell his clean scent, losing sense of himself; _hunger food kill humans mate kill protect mate matematemate_

Ai's humming in his ear, chest vibrating.

“Not yet, Sousuke, soon,” he whispers, “when I'm fully sated.”

_Find food, provide, protect Ai-_

“ _I can get my own food, my Sousuke,”_ Ai purrs, _“you can stay with me, you love my singing, don't you?”_

“Yes, I love it, I love you.”

Ai draws up above him, cradling his head in gentle hands. Moonlight drifts through the water, shifting above him, and Sousuke has never seen a sight so captivating in his life. His heart and body aches at the mere thought of him ever leaving, ever abandoning him. He couldn't bear it.

“ _Do you, Sousuke?”_ he says quietly, _“do you really?”_

“Yes, yes!” Sousuke replies, earnestly, eagerly, holding fast to Ai's waist.

Ai's lips taste of blood as they rake over his own, and they hurt, they hurt so wonderfully, his tongue pushing past with its barbs, ones that stripped human skin. Ai tastes the inside of his mouth, drawing his blood, and Sousuke's heart sings at the thought of a part of him forever inside Ai, carried in his perfect body until the day they die. He moans, dragging his own tongue across Ai's, and Ai smiles against him.

“ _I love you, Sousuke.”_

Sousuke's heart is bursting with joy as Ai draws away, smiling so tenderly at him, and it's eager beats tinge the water between them with his blood.

-

**Author's Note:**

> Thank you for reading :>


End file.
